Light beam display

ABSTRACT

A laser beam display includes at least a first and second plurality of laser beam sources, each of which may preferably be an array of semiconductor lasers, providing a plurality of laser beams in an optical path so as to reflect off of reflective facets of a movable reflector and illuminate a display screen. In a color display, each column of the laser array corresponds to a separate primary color. The separate rows of each array correspond to independently activated but simultaneously driven scan lines to be illuminated by the laser beam scanning apparatus. The plural laser beam arrays subdivide the width of the screen into smaller scan segments to increase the scanning angle or increase the horizontal scanning speed of the apparatus. Tilted facets illuminate different vertical sections of the screen with the laser beams as the reflector rotates. A scan format employing simultaneously illuminated diagonal scan tiles provides optimal use of the plural laser beam arrays.

RELATED APPLICATION INFORMATION

This application is a continuation of U.S. Ser. No. 09/169,163 filedOct. 8, 1998, now U.S. Pat. No. 6,175,440 which in turn is acontinuation-in-part of U.S. Ser. No. 08/887,947 filed on Jul. 3, 1997,now U.S. Pat. No. 6,008,925 which in turn is a continuation of U.S. Ser.No. 08/162,043 filed on Feb. 2, 1994, now U.S. Pat. No. 5,646,766. Thedisclosure of the above noted patent and applications are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methods and apparatus for displaying animage by employing a light beam or beams.

2. Description of the Prior and Related Information

High resolution displays have a variety of applications, includingcomputer monitors, HDTV and simulators. In such applications, theprimary considerations are resolution, maximum viewable area, cost andreliability. Although a number of approaches have been employedincluding CRT displays, rear projection and front projection displays,plasma displays and LCDs, none of these have been able to satisfactorilyprovide all the above desirable characteristics. In other displayapplications, such as control panel displays, and vehicle and aircrafton-board displays, resolution is of less importance than brightness,compact size and reliability.

Although lasers potentially can provide many advantages for displays ofboth types noted above, laser based displays have not been widelyemployed. This is due in large part to limitations in the laser scanningengines available. One conventional approach to scanning a laser beamemploys a rotating mirror to scan the laser beam in a linear directionas the mirror rotates. Typically, the mirror is configured in a polygonshape with each side corresponding to one scan length of the laser beamin the linear direction.

An example of such a rotating polygon laser beam scanner is illustratedin FIG. 1. The prior art laser beam scanning apparatus shown in FIG. 1employs a polygon shaped mirror 1 which receives a laser beam providedby laser 2 and deflects the laser beam in a scanning direction X as thepolygon 1 rotates. It will be readily appreciated from inspection of thegeometry of FIG. 1 that such a rotating polygon system has the abilityto scan the laser beam through a maximum angle of 180° with a scan lineduration determined by the rotational speed of the polygon divided by N,where N is the number of polygon sides. Also, it will be appreciatedthat for large N the scan angle may be significantly reduced below 180°.Thus, for the eight sided polygon configured as illustrated in FIG. 1,the laser beam is scanned through an angle of about 90° with theduration of each scan line being ⅛ the period for one rotation of thepolygon.

The laser scanning apparatus illustrated in FIG. 1 has the advantage ofbeing quite simple, and is suitable for some applications. Nonetheless,this conventional laser scanning apparatus is not suitable for highresolution displays since the inherent limitations of such apparatusmake it difficult to simultaneously achieve a high degree of resolution,high scanning speed and a large scanning angle. More specifically, ahigh degree of resolution requires a relatively large polygon with fewsides. That is, if the laser beam is to provide accurate information asit is scanned along the scan direction, modulation of the laser beam asit traverses the surface of the polygon side must unambiguously providediscrete points in the scan direction. Thus, each side of the polygonmust increase with the beam diameter and the number of discrete scanpoints (n). Therefore, high resolution, corresponding to a very largenumber (n) of discrete scan points, in general requires large polygonsides. This limitation is particularly significant where the scannedbeam target surface is located close to the polygon mirror. Also, asnoted above, the scan angle is reduced as the number of polygon sides isincreased. Therefore, high resolution and high scan angle require alarge polygon with relatively few sides.

The requirements of a large polygon with few sides, however, mitigateagainst a high scan rate and thus severely restricts resolution and/orrefresh rate of a display based on such a laser beam scanning apparatus.As indicated above, scanning speed is directly related to the number ofpolygon sides. Therefore, a polygon with few sides requires very highspeed rotation to achieve high scanning speed. Rotating a large polygonat high speed creates mechanical problems, however. In particular, highspeed rotation introduces vibrations, stress on the moving parts, andreduced accuracy in the registration of the mirror relative to the laserbeam. These factors collectively limit the rotational speed of themirror, and hence the beam scan rate.

As noted above, another category of display application of increasingimportance requires relatively small but robust displays having goodbrightness and acceptable resolution for graphics, such as maps, andtext. Such displays have significant applications in automobiles andother vehicles. In such applications, a laser based display haspotential advantages due to its brightness. However, once again, theexisting laser beam scanning apparatus are not well suited. Inparticular, the optical path of the laser beam is quite short in suchapplications due to the compact space available for the display. Thisrequires the size of the rotating polygon to be increased. However,mechanical instability is associated with large rotating polygons and isa serious detriment for such applications, where reliability iscritical.

Accordingly, it will be appreciated that a need thus presently existsfor an improved laser beam display apparatus.

SUMMARY OF THE INVENTION

The present invention provides a display apparatus and method employingscanning of light beams through a large scan angle at high speed andwith a high degree of accuracy to provide a high resolution display. Thepresent invention further provides a light beam display apparatus havinga relatively compact configuration for a given screen size and which isrelatively free of vibration or other mechanical problems even at highresolutions and refresh rates.

The present invention provides a laser beam display which includes afirst and second plurality of light beam sources, each of which maypreferably be an array of semiconductor lasers, providing a plurality oflight beams in an optical path so as to simultaneously reflect offplural reflective facets of a movable reflector and illuminate a displayscreen. In a color display, each column of the laser array correspondsto a separate primary color and the separate rows of the arraycorrespond to independently activated but simultaneously driven scanlines to be illuminated by the laser beam scanning apparatus. The plurallaser beam arrays subdivide the width of the screen into smaller scansegments to increase the scanning angle or increase the horizontalscanning speed of the apparatus. A scan format employing simultaneouslyilluminated diagonal scan tiles provide optimal use of the plural laserbeam arrays.

More specifically, in a preferred embodiment the light beam scanningapparatus of the present invention includes an input for receiving videodata including a plurality of horizontal lines of display informationand a high speed memory for storing the video data for plural horizontallines. First and second light diode arrays are provided, each comprisinga plurality of rows and at least one column. A control circuit controlssimultaneous activation of the light beams in accordance with the videodata from plural horizontal lines stored in the high speed memory. Anoptical path including a movable reflector directs the simultaneouslyactivated plural beams from both diode arrays off of at least two facetsof the movable reflector to the display screen.

In a further aspect the present invention provides a method ofdisplaying information on a display screen employing a plurality oflight beam sources and a rotatable reflector having a plurality ofreflective facets tilted at different angles. A first plurality of lightbeams are directed to a first facet of the movable reflector tilted at afirst angle, and from the first facet to the display screen, from thefirst light beam source. A second plurality of light beams are directedto a second facet of the movable reflector tilted at a different angle,and from the second facet to the display screen, from the second lightbeam source. The reflector is rotated so as to cause the first andsecond plurality of light beams to simultaneously trace out parallelmultiline scan segments on the display screen. The parallel scansegments are displaced vertically on the screen by the tilted facets soas to provide a generally diagonal configuration on the display screen.The entire screen is illuminated by tiling the screen with thesediagonal scan patterns as different tilted facets rotate into theoptical path of the light beams.

Further features and advantages of the present invention will beappreciated from the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top schematic view of a prior art laser scanning apparatus.

FIG. 2 is a schematic drawing of a laser beam display in accordance witha preferred embodiment of the present invention.

FIG. 3 is a schematic drawing of a scan pattern in accordance with theoperation of the laser display of the present invention.

FIGS. 4A-4C are schematic drawings of a scan pattern provided inaccordance with a preferred mode of operation of the laser beam displayof the present invention.

FIG. 5 is a block schematic drawing of the circuitry of a preferredembodiment of the laser beam display of the present invention.

FIG. 6 is a partial cutaway view of a laser diode array in accordancewith the present invention.

FIGS. 7A and 7B illustrate an alternate embodiment of the presentinvention employing a fiber optic laser beam delivery head.

FIG. 8 illustrates two fiber optic delivery heads in accordance with thealternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, a preferred embodiment of the laser beam displayapparatus of the present invention is illustrated in a schematic drawingillustrating the basic structure and electronics of the embodiment. Thedimensions of the structural components and optical path are not shownto scale in FIG. 2, and the specific dimensions and layout of theoptical path will depend upon the specific application.

As shown in FIG. 2, the laser beam scanning apparatus includes amultifaceted polygon reflector 32. The polygon shaped reflector 32 ispreferably coupled to a variable speed motor 36 which provides for highspeed rotation of the reflector 32 such that successive flat reflectivefacets on the circumference thereof are brought into reflective contactwith the laser beams. The rotational speed of the reflector 32 ismonitored by an encoder (not shown) which in turn provides a signal tomotor control circuit (which may be included in the control electronics220). The motor control circuitry, power supply and angular velocitycontrol feedback may be as described in U.S. Pat. No. 5,646,766 thedisclosure of which is incorporated herein by reference. Although awheel shaped multi-faceted reflector 32 is presently preferred, it willbe appreciated that other forms of movable multi-sided reflectors mayalso be employed to consecutively bring reflective flat surfaces inreflective contact with the laser beams. Such alternate reflectors maybe actuated by any number of a wide variety of electromechanicalactuator systems, including linear and rotational motors, with aspecific actuator system chosen to provide the desired speed of thefacets for the specific application.

The apparatus of FIG. 2 further includes a first source 200 of aplurality of laser beams 202, which plural beams may include beams ofdifferent frequencies/colors as discussed in detail below, and anoptical path for the laser beams between the laser source 200 and adisplay screen 206. A second source 300 of a plurality of beams 302 isalso provided, with a generally parallel optical path to display screen206. As one example of a presently preferred embodiment the lasersources 200, 300 may each comprise a rectangular array of laser diodeshaving a plurality of rows and at least one column. A monochrome displaymay have a single column for each diode array whereas a color displaymay have 3 columns. A color array thus provides the 3 primary colors foreach row. The number of rows corresponds to the number of parallel scanlines traced out on the display screen 206 by each diode array. Forexample, 14 rows of diodes may be employed. Each two-dimensional diodearray 200, 300 may thus provide from 1 to 42 separate laser beams 202,302 simultaneously (under the control of control electronics 220,discussed below). Other sources of a plurality of laser beams may alsobe employed. For example, a single beam may be split into a plurality ofindependently modulated beams using an AOM modulator, to therebyconstitute a source of a plurality of beams. Such an approach forcreating plural beams using an AOM modulator is described in U.S. Pat.No. 5,646,766, incorporated hereby by reference.

The optical path is configured such that the laser beams intercept therotating polygon 32 in a manner so as to provide a desired scan rangeacross display screen 206 as the polygon rotates. The optical path willdepend on the specific application and as illustrated may employ one ormore reflective optical elements 212 to increase the path length. Also,one or more lenses 214, 314, may be provided for each laser beam 202,302 so as to focus the beams with a desired spot size on display screen206.

It will be appreciated that a variety of modifications to the opticalpath and optical elements illustrated in FIG. 2 are possible. Forexample, additional optical elements may be provided to increase theoptical path length or to vary the geometry to maximize scan range in alimited space application. Alternatively, the optical path may notrequire any path extending elements such as reflective element 212 in anapplication allowing a suitable geometry of beam sources 200, 300,reflector 32 and screen 206. Similarly, additional focusing orcollimating optical elements such as lenses 214 may be provided toprovide the desired spot size for the specific application. In otherapplications the individual focusing elements 214, 314 may be combinedfor groups of diodes. For example, all the diodes in a single row of adiode array may be focused by a single optical focusing element 214,314. In yet other applications, the focusing elements may be dispensedwith if the desired spot size and resolution can be provided by thelaser beams emitted from the diode arrays 200, 300 itself. The screen206 in turn may be either a reflective or transmissive screen with atransmissive diffusing screen being presently preferred for compactdisplays or where a high degree of brightness is desired.

As further illustrated schematically in FIG. 2, the laser beam sources200, 300 provide the plurality of laser beams, illustrated generally bybeams 202, 302 in FIG. 2, simultaneously on respective facets 204,304 ofthe rotating reflector 32. In particular, plural beams 202 aresimultaneously directed to respective spots or pixels on display 206 viafacet 204. Plural beams 302 via facet 304 are in turn simultaneouslydirected to a different set of pixels on display 206. A plurality ofbeams from a laser source 200 or 300 may also simultaneously illuminatea single pixel. In particular, in a color display all three diodes in asingle row of the diode array may simultaneously illuminate a singlepixel. Even in a monochrome display application plural beams may becombined at a single pixel to provide increased brightness. Thiscombination of plural beams to plural pixels is illustrated generally inFIG. 2 by the four laser beams simultaneously being directed to display206, each of which preferably includes plural distinct component beamsof different frequency or color. The specific manner in which the beams202, 302 trace out the video data on the screen 206 will be described inmore detail below in relation to FIGS. 3 and 4A-4C.

Still referring to FIG. 2, the diode arrays 200, 300 are driven bycontrol signals provided from control electronics 220 which in turnreceives the video information to be displayed from video data source100. Video data source 100 may comprise any source of video informationto be displayed on display 206 and may comprise a source of analog ordigital video signals in any of a variety of known formats. Controlelectronics 220 converts the video data provided from source 100 todigital form if necessary and then to a parallel scan format adapted forthe specific scan pattern provided by the diode arrays 200, 300, asdescribed in more detail below.

Referring to FIG. 3, the manner in which the multiple diode arrays 200,300 simultaneously provide plural beams to plural facets and provide anincreased scanning speed and/or scanning angle for the display, isillustrated.

In FIG. 3, a front view of display screen 206 is schematicallyillustrated with the usable part of the screen having a width dimension(W) and a height dimension (H). The display shown is for a colordisplay, with three beams of different color light simultaneouslyactivated and focused on each pixel 210, 310, from each of the lasersources 200, 300, respectively. These individual beams preferablycorrespond to the three primary colors red, blue and green to provide acolor image on display 206. Thus, for the two sets of pixels 210, 310illustrated in FIG. 3, red, blue and green laser beams (RBG) areprovided simultaneously by laser sources 200, 300.

As shown in FIG. 3, the width dimension (W) of display screen 206 may besubdivided into plural horizontal scan segments corresponding to thenumber of diode arrays. Although two horizontal scan segments 208, 308are illustrated, corresponding to two diode arrays 200, 300, the numberof such segments and diode arrays is not so limited and generally may be2-10 or greater in number. In the first horizontal scan segment 208 afirst plurality of beams is provided from diode array 200 to plural rowsof pixels 210 as illustrated in FIG. 3 to trace out a first set of scanlines 212. At the same time a plurality of beams from diode array 300illuminate plural rows of pixels 310 which trace out a second set ofscan lines 312 in the second horizontal scan segment 308. Theserespective beams, scanned along plural horizontal scan linesby rotationof reflector 32, thus generate a first vertical scan segment 316.Accordingly, it will be appreciated that for rotation of the polygon 32through an angular range corresponding to a single facet width, thewidth scanned out on the screen 208 will be double that provided bysingle source of laser beams. Accordingly, a concomitant increase inscanning speed and/or screen size is provided.

The vertical range or height (H) of the display screen 208 is scannedout by repeating the parallel scanning for each of the vertical scansegments 316. It will be appreciated that to consecutively scan thelaser beams over the respective vertical scan segments 316, some meansis required for shifting the beams vertically to cover the entirevertical distance H shown in FIG. 3. Several different such means forvertically shifting the beams are described in U.S. Pat. No. 5,646,766the disclosure of which is incorporated herein by reference.

In a presently preferred embodiment the vertical shifting of the beamsis achieved by using facets of the rotating polygon 32 which are angledat differing degrees relative to the axis of rotation of the polygon 32.Each differing facet angle thus corresponds to a different verticalposition on the display screen 206 allowing the different vertical scansegments 316 to be traced out as the laser beams 202, 302 interceptconsecutive ever more tilted facets. Therefore, one rotation of thepolygon 32 will result in all the vertical scan segments 316 beingilluminated providing an image on the entire usable surface area ofdisplay screen 206.

In accordance with the use of tilted facets of the rotating polygonreflector 32 as a means for vertically shifting the laser beams, amodification of the scanning format of FIG. 3 is preferably employed. Inparticular, a diagonal “tiling” scan format is preferably employed. Thisscan format is illustrated in FIGS. 4A-4C, which Figures showconsecutive sections of the screen 206 being illuminated by the laserbeams in a tiling pattern. The example of the diagonal tiling scanformat shown in FIGS. 4A-4C includes 14 rows of laser diodes beingsimultaneously provided from each of laser beam sources 200 and 300 anda rotating polygon reflector 32 having N facets (or an integer multiplethereof, plus any “dead” facets between frames). Each of the N facets istilted at a different angle, the angle for each facet corresponding to adifferent vertical position on the display 206 as generally indicated tothe left of each vertical scan segment in FIGS. 4A-4C. The numbering ofthe facets for FIGS. 4A-4C is such that facet 1 corresponds to the facettilted to illuminate the top of the display screen 206 whereas facet Nis tilted to illuminate the bottom of display screen 206.

Referring first to FIG. 4A, the scan pattern begins with a first scantile 400-1 illuminated by the laser beams from the first laser beamsource, i.e., diode array 200, striking facet 1 of the rotating polygonreflector 32 and being scanned across the width of a horizontal scansegment 208. In this way, for the example of a 14 row diode array 100,14 rows of video information are scanned in parallel across thehorizontal scan segment in the first tile 400-1. The number of pixels ofresolution in the horizontal direction depends on the video data and theparticular application; for example, 320 pixels is a specific examplefor a high resolution display, but fewer or greater pixels may beprovided.

Referring to FIG. 4B, the scan pattern is illustrated after the rotatingpolygon reflector 32 has rotated facet 1 into the optical path of thesecond laser beam source, i.e., diode array 300, and the second facet isin the optical path of the first laser beam source. Rotation of thereflector at this time scans the laser beams from the first and secondlaser beam sources over the two diagonally configured tiles 400-2illustrated in FIG. 4B. This diagonal tiling scan pattern continues withthe next consecutive tilted facet (facet 3) entering the optical path ofthe laser beam sources to illuminate diagonal tiles 400-3 as illustratedin FIG. 4C. This pattern continues until the entire display screen 206has been illuminated by the laser beams. As used herein, the term“parallel scan segments” will refer to the tiles which are scanned outtogether in parallel, e.g., the tiles 400-2 in FIG. 4B and the tiles400-3 illustrated in FIG. 4C.

It will be appreciated that if additional laser beam sources areprovided the tiling pattern illustrated in FIGS. 4A-4C will addadditional horizontal scan segments. The diagonal tiling pattern in turnwill extend across the entire width of the display with the number oftiles simultaneously illuminated equal to the number of horizontal scansegments. Thus, for example, if three diode arrays were employed thescan pattern corresponding to FIGS. 4B and 4C would include threediagonally spaced tiles illuminated simultaneously. Similarly, moretiles will be simultaneously illuminated for greater numbers of laserbeam sources, which as noted above may be 2-10 in number or even greaterif desired for the particular application.

It will be appreciated by those skilled in the art that the ability toprovide multiple tiles each multiple beams deep on display screen 208has significant advantages in display applications. The above exampleusing a 14 ×3 rectangular diode array provides a reasonable compromisebetween scanning speed and size of the diode arrays 200, 300 and a 504line color image could thus be provided onto the display screen 206 by36 scans of the laser beams in the horizontal direction across thedisplay screen 206. Thus, 36 independently tilted facets could providescanning of all 504 lines of the display 206 in a single rotation ofrotating polygon 32. Therefore, the combination of the two-dimensionaldiode arrays 200, 300 and a multifaceted tilted facet polygon 32 allowsthe size and rotational velocity of the rotating polygon 32 to bereduced without compromising resolution or display size. It will beappreciated by those skilled in the art that a variety of differentcombinations of diode array dimensions and/or rotating polygon 32configurations may be provided depending upon the specific requirementsof any given application including cost, space available for the laserbeam scanning apparatus, screen size desired, total number of scan linesrequired, etc. Furthermore, while a rectangular array of diodes has theadvantage of ease of layout and adapts well to a rectilinear scanning oflines in a typical display application, it will be appreciated thatother diode array configurations can also be employed.

The display of the present invention has a further advantage for colordisplay applications over conventional color displays. Conventionaldisplays, e.g., cathode ray tube (CRT) displays, cannot providedifferent colors precisely at a single pixel region since thephosphorous employed must have different characteristics for thedifferent colors and must be separated. Therefore, the individualcolored pixels in CRT displays are arranged side by side in a mannerwhich optically is perceived as a single pixel by the eye. For very highresolutions, however, the limitation of having to provide three separatepixel regions for each pixel of the display can negatively impact on theresolution of the display. The present invention, however, can place thethree distinct color laser beams on precisely the same pixel spot,whether for a reflective or transmissive type display screen 208,thereby avoiding a side by side placement of the color pixel regions.

Referring to FIG. 5, a block schematic drawing of the controlelectronics 220 is illustrated. The control electronics receives a videoinput signal from the video source along line 222. As noted above, theinput signal may be of any of a number of conventional formats, e.g.,NTSC interlaced or progressive scan formats, and may be either analog ordigital in nature. The signal is provided to video interface 286 which,in the case of an analog input video signal provided along line 222,will provide analog to digital conversion of the input signal. Videointerface 286 outputs the digital video data in serial format along line288 to serial to parallel converter 290. Serial to parallel converter290 operates in conjunction with video RAM controller 292 to convert theserial video data, which may typically be in a raster scan format, to aparallel scan format corresponding to the parallel tiling scan patternillustrated in FIGS. 4A-4C. Video RAM controller 292 will include a highspeed temporary memory such as a random access memory (RAM) or FIFObuffer of sufficient capacity to hold at least one parallel scan segmentof video data, e.g., corresponding to two scan tiles. The video syncsignals in the video data provided along line 288 in turn are passedthrough beam timing logic 294 which synchronizes the parallel scansegments with the start of frame and start of line signals typicallyprovided in an analog or digital video signal and provides the parallelscan timing signals to the video RAM controller 292. The output of videoRAM controller 292 in turn is provided independently to the red, greenand blue video driver circuitry 278, 282 and 280, respectively, in theform of digital color intensity signals to allow a gray scale colorcontrol for a desired palette of colors for the color display. The videodriver circuitry in turn converts the digital color intensity signals toanalog drive signals provided to the individual diodes in the diodearray 200 (or 300, not shown in FIG. 5) to turn them on and off with anintensity related to the gray scale drive signal and provide the desiredcolor for each pixel.

Referring to FIG. 6, one embodiment of the diode array 200 isillustrated in a perspective cutaway view (diode array 300 will be ofidentical structure and hence is not shown). As shown, the diode array200 is provided by a compact configuration of individual laser diodes230, e.g., color specific diodes, 230R, 230B and 230G. The individuallaser diodes 230 are configured in a compact housing 240 which in turnmay be mounted to a printed circuit board or other suitable supportstructure via mounting bracket 242. Alternatively, adhesive or othersuitable mounting techniques well known to those skilled in the art maybe employed. As further illustrated in FIG. 6, the individual laserdiodes may preferably include a focusing lens cap 232 affixed to theoutput portion of the laser diode to provide an initial focusing of thelaser beam. The power and control signals in turn are provided to theindividual laser diodes through a suitable electrical connection, suchas flex circuit 250 illustrated in FIG. 6. Flex circuit 250 iselectrically and mechanically coupled to the housing 240 and individualdiodes 230 via a plug connector 252. It will be appreciated that avariety of other electrical connection approaches may also be employed,however, including individual electrical connections to each laser diode230 or provision of independent printed circuit boards for each columnof the diode array. The flex circuit 250 is coupled to controlelectronics 220 which in turn is preferably configured on a printedcircuit board. The control electronics may, however, be provided on thesame circuit board which receives mounting bracket 242 or to which thehousing 240 is otherwise directly mounted.

Referring to FIGS. 7A and 7B, an alternate embodiment of the lasersource 200 and associated electronics is illustrated which employs afiber optic laser beam delivery head which may be advantageous forapplications having space limitations or other constraints requiring acompact laser delivery head.

As shown in FIG. 7A, the fiber optic laser beam delivery head 260includes a bundle of optical fibers 262 arranged in a compactrectangular array within a housing 264. The ends of each of the opticalfibers 262 may preferably include a focusing end cap element 266 as moreclearly illustrated in FIG. 7B. Although the illustration of FIG. 7B isnot intended to show the accurate optical shape of the focusing element266, it does illustrate the compact manner in which it can be integratedwith the optical fiber 262. Referring again to FIG. 7A, the opposite endof each optical fiber 262 is coupled to the output of a correspondinglaser diode 268. An optional additional collimator and focuser 270 maybe provided at the output of the individual laser diodes 268 dependingupon the length of the optical fiber 262 and the output characteristicsof the laser diodes 268. The individual laser diodes 268 and optionalcollimator/focusing elements 270 for each column of the diode array maybe mounted on separate circuit boards 272, 274, 276 as illustrated inFIG. 7A or a single circuit board, space permitting. The length of theoptical fibers 262 is chosen to enable the laser array delivery head 260to be conveniently mounted in the desired optical path relative to thedisplay screen 206. The individual laser diodes 268 in turn are poweredby respective red, blue, and green video driver circuitry 278, 280, 282which form part of control electronics 220 as described above. The videodriver circuitry may be configured on the same circuit boards 272, 274,276 as the laser diodes or on a separate circuit board depending on thespecific application and space requirements.

Referring to FIG. 8, a compact circuit board implementation of the laserdiodes driving plural fiber optic delivery heads is illustrated. Asshown, two fiber optic delivery heads 330, 332 are coupled to aplurality of laser diodes 334 via optical fibers 336. The individuallaser diodes 334 may be configured on a single circuit board 338 asillustrated or may be split into separate boards depending on the spacerequirements of the specific application. Also, as in relation to theembodiment described above in relation to FIG. 7A, opticalcollimator/focusing elements 340 may be provided between the output ofthe laser diodes and the optical fibers. As also more clearly shown inFIG. 8, the control electronics splits the video driver signals for eachcolor (red being illustrated in FIG. 8) into parallel drive signalscorresponding to the two fiber optic delivery heads.

While the foregoing detailed description of the present invention hasbeen made in conjunction with specific embodiments, and specific modesof operation, it will be appreciated that such embodiments and modes ofoperation are purely for illustrative purposes and a wide number ofdifferent implementations of the present invention may also be made.Accordingly, the foregoing detailed description should not be viewed aslimiting, but merely illustrative in nature.

What is claimed is:
 1. A light beam display apparatus, comprising: adisplay screen having a vertical and a horizontal dimension; a firstplurality of light beam sources configured in an array comprising aplurality of rows and at least one column; a second plurality of lightbeam sources configured in an array comprising a plurality of rows andat least one column; a control circuit for simultaneously andindependently activating said first and second plural light beamsources; and an optical path including a movable reflector having aplurality of reflective facets between the display screen and the firstand second light beam sources for directing said simultaneously andindependently activated plural light beams to the display screen viarespective first and second facets of the movable reflector tosimultaneously and independently illuminate different horizontal regionsof the display each comprising plural horizontal pixels.
 2. A light beamscanning apparatus as set in claim 1, wherein the movable reflector is arotatable polygon and wherein the light beam scanning apparatus furthercomprises a motor for rotating the polygon at a predetermined angularspeed thereby bringing successive facets into the optical path so as tointercept the plural light beams.
 3. A light beam scanning apparatus asset in claim 1, wherein the light beam sources in each column of thearray correspond to a different color of light.
 4. A light beam scanningapparatus as set out in claim 3, wherein the array has three columns andwherein each column corresponds to a light beam source having a primarycolor.
 5. A light beam scanning apparatus as set out in claim 1, whereinthe plurality of light beam sources comprise semiconductor lasers.
 6. Alight beam scanning apparatus as set out in claim 5, wherein the lightbeam sources comprise semiconductor diodes.
 7. A light beam scanningapparatus as set out in claim 1, further comprising means for shiftingthe light beams so as to illuminate different vertical scan segments ofthe display screen.
 8. A light beam scanning apparatus as set out inclaim 7, wherein the means for shifting comprises a plurality ofreflective facets configured on the movable reflector tilted atdiffering degrees.
 9. A light beam scanning apparatus as set out inclaim 8, wherein movable reflector is a rotating polygon and wherein thetilted facets are tilted relative to the axis of rotation of the polygonso as to direct the light beams to varying vertical scan segments on thedisplay screen.
 10. A light beam scanning apparatus comprising: an inputfor receiving video data, the video data including a plurality ofhorizontal lines of display information; a display screen; a firstplurality of light beam sources configured in an array comprising aplurality of rows and at least one column; a second plurality of lightbeam sources configured in an array comprising a plurality of rows andat least one column; a movable reflector having a plurality ofreflective facets; a memory for storing a plurality of horizontal linesof video data; a control circuit for simultaneously and independentlyactivating said light beam sources in accordance with video data fromplural horizontal lines stored in said memory; and an optical pathbetween the display screen, the movable reflector and the first andsecond plurality of light beam sources for directing said simultaneouslyand independently activated plural beams to at least two facets of themovable reflector and to the display screen, wherein the movablereflecting scans each of the first and second plurality of light beamsover only a portion of a horizontal line each portion comprising pluralhorizontal pixels.
 11. A light beam scanning apparatus as set in claim10, wherein the movable reflector is a rotatable polygon and wherein thelight beam scanning apparatus further comprises a motor for rotating thepolygon at a predetermined angular speed thereby bringing respectivefacets into the optical path so as to intercept the plural light beams.12. A light beam scanning apparatus as set in claim 10, wherein each ofthe arrays of light beam sources have plural columns which correspond toa different color of light.
 13. A light beam scanning apparatus as setout in claim 12, wherein each array has three columns and wherein eachcolumn corresponds to a light beam source of a primary color.
 14. Alight beam scanning apparatus as set out in claim 10, wherein theplurality of light beam sources comprise semiconductor lasers.
 15. Alight beam scanning apparatus as set out in claim 10, wherein each arraycomprises an array of fiber optic fibers mounted in an array and coupledoptically to respective light emitting diodes.
 16. A method ofdisplaying information on a display screen employing a plurality oflight beam sources and a movable reflector having a plurality ofreflective facets, comprising: directing a first plurality of lightbeams to a first facet of the movable reflector, and from the firstfacet to the display screen; directing a second plurality of light beamsto a second facet of the movable reflector, and from the second facet tothe display screen; moving the reflector so as to cause the first andsecond plurality of light beams to simultaneously and independentlytrace out in a first direction parallel multi-line scan segments on thedisplay screen each scan segment comprising plural pixels in said firstdirection.
 17. A method as set out in claim 16, wherein said displayscreen has a generally rectangular configuration and wherein said firstdirection corresponds to the horizontal dimension of said screen andsaid second direction corresponds to the vertical dimension of saidscreen.
 18. A method as set out in claim 17, wherein the entire displayis illuminated by sequentially illuminating parallel scan segmentsemploying different sets of tilted facets in the optical path of thelight beams.
 19. A method as set out in claim 18, wherein the parallelscan segments each have a plurality of different horizontal scan linesof video information.
 20. A method as set out in claim 17, wherein theparallel scan segments comprise diagonally adjacent rectangular segmentsof the display screen.